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From Mike Tutkowski <mike.tutkow...@solidfire.com>
Subject Re: [PROPOSAL] Provide Option to Quiesce VMs While Taking Snapshots
Date Mon, 30 Sep 2013 22:03:48 GMT
VM quiescing should be sufficient for hypervisor snapshots, though, because
you are presumably snapping the disks and the memory.


On Mon, Sep 30, 2013 at 4:02 PM, Mike Tutkowski <
mike.tutkowski@solidfire.com> wrote:

> I would say 'no'. Let's say you have a DB app running in your host OS and
> it's in the middle of writing a transaction to a data disk...quiescing the
> VM - without quiescing the DB app (like SQL Server via VSS) - does not give
> you a properly quiesced snapshot on the data disk - just a point-in-time
> snapshot.
>
>
> On Mon, Sep 30, 2013 at 3:52 PM, Chiradeep Vittal <
> Chiradeep.Vittal@citrix.com> wrote:
>
>> Is VM Quiescing sufficient to ensure consistency of the snapshot?
>>
>>
>> On 9/30/13 2:43 PM, "SuichII, Christopher" <Chris.Suich@netapp.com>
>> wrote:
>>
>> >CloudStack currently snapshots vm disks by taking hypervisor snapshots.
>> >However, when implementing the storage subsystem API interface
>> >takeSnapshot(), the VM associated with the requested volume is not
>> >quiesced since a hypervisor snapshot is not necessarily taken. When
>> >creating a storage level snapshot, there are ways around this and
>> >'quiescing' the vm without actually quiescing it (through hypervisor
>> >APIs). I would like to propose that there be an option to quiesce VMs
>> >when taking snapshots both manually and through recurring snapshot
>> >policies. One issue I see with this is that this option is not always
>> >applicable. If the default storage provider is used, a hypervisor
>> >snapshot will be taken and therefore the VM will always be quiesced. Some
>> >storage providers may not respect the user's request to quiesce. Because
>> >of this, I suggest that the option be shown to the user as 'Quiesce VM
>> >(if applicable)'. This indicates to the user that the option will be
>> >passed to the management server and respected if possible.
>> >
>> >I will work on formalizing a full functional spec if needed but wanted to
>> >get this up for discussion ASAP.
>> >
>> >I have created a JIRA ticket:
>> >https://issues.apache.org/jira/browse/CLOUDSTACK-4774
>> >
>> >Thanks,
>> >Chris
>> >--
>> >Chris Suich
>> >chris.suich@netapp.com<mailto:chris.suich@netapp.com>
>> >NetApp Software Engineer
>> >Data Center Platforms ­ Cloud Solutions
>> >Citrix, Cisco & Red Hat
>> >
>>
>>
>
>
> --
> *Mike Tutkowski*
> *Senior CloudStack Developer, SolidFire Inc.*
> e: mike.tutkowski@solidfire.com
> o: 303.746.7302
> Advancing the way the world uses the cloud<http://solidfire.com/solution/overview/?video=play>
> *™*
>



-- 
*Mike Tutkowski*
*Senior CloudStack Developer, SolidFire Inc.*
e: mike.tutkowski@solidfire.com
o: 303.746.7302
Advancing the way the world uses the
cloud<http://solidfire.com/solution/overview/?video=play>
*™*

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